The present invention relates generally to rotary machines, and more particularly to a rotor insert assembly for rotary machines such as steam and gas turbines.
Rotary machines include, without limitation, turbines for steam turbines and compressors and turbines for gas turbines. A steam turbine has a steam path that typically includes, in serial-flow relationship, a steam inlet, a turbine, and a steam outlet. A gas turbine has a gas path which typically includes, in serial-flow relationship, an air intake (or inlet), a compressor, a combustor, a turbine, and a gas outlet (or exhaust nozzle). Gas or steam leakage, either out of the gas or steam path or into the gas or steam path, from an area of higher pressure to an area of lower pressure, is generally undesirable. For example, any gas path leakage in the turbine or compressor area of a gas turbine, between the rotor of the turbine or compressor and the circumferentially surrounding turbine or compressor casing, will lower the efficiency of the gas turbine leading to increased fuel costs. Also, steam-path leakage in the turbine area of a steam turbine, between the rotor of the turbine and the circumferentially surrounding casing, will lower the efficiency of the steam turbine leading to increased fuel costs.
It is known in the art of rotary machines that contact between stationary and rotating parts, for example, a brush seal and a rotor in a steam turbine, typically results in temporary deformation of the rotor due to heat generated by the frictional forces created by the rubbing of the brush seal against the rotor. As a result of such deformation, the heating of the rotor and the direct forces caused by the brush seal typically cause the rotor to become unbalanced thus producing a xe2x80x9cwobblingxe2x80x9d effect on the rotor. The wobbling effect increases the vibration in the rotary machine thereby enlarging the gap defined between the stationary and rotating parts. In some instances, the deformation typically causes a scoring of the rotor thus resulting in costly repairs to the rotor and the brush seal. Consequently, the efficiency of the rotary machine decreases due to the increase in gas or steam leakage through the gap created by either the wobbling effect or the scoring of the rotor.
Accordingly, there is a need in the art for a rotary machine having improved thermal control between stationary and rotating components.
One embodiment of the present invention comprises an insert assembly for a rotary machine wherein the rotary machine comprises a rotor and a casing. The rotor comprises a generally longitudinally-extending axis. The casing is generally coaxially aligned with the axis. The casing circumferentially surrounds and is radially spaced apart from the rotor. The insert assembly comprises a channel circumferentially disposed on the rotor and an insert circumferentially disposed in such channel such that the insert assembly is configured to thermally isolate frictional heat from the rotor to the insert.